I havn't tested this with your particular code, but I remember having a similar problem, and it was solved like this, by adding some explicit returns:

# instead of your if, split it up into 2 lines
#  return unless -d;
#  $File::Find::prune = 1 if /[LP]\d{8}$/;  # Don't recurse.
#  print "$File::Find::dir/$_/\n" if /[LP]\d{8}$/;

 return unless -d;
 return unless $_  =~ /[LP]\d{8}$/;
 $File::Find::prune = 1; # don't descend
  print "$File::Find::dir\n";
  print "$file::Find::name\n";

# or possibly better

return $File::Find::prune = 1 if /[LP]\d{8}$/;  # Don't recurse.
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